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Characterization of curcumin nanocrystals in capillary electrophoresis
Dvořáková, Amálie ; Křížek, Tomáš (advisor) ; Sobotníková, Jana (referee)
This Bachelor thesis deals with the characterization of curcumin nanocrystals using capillary electrophoresis with UV-VIS and laser-induced fluorescence (LIF) detection. Curcumin is a natural polyphenolic substance with many biological effects. Its low solubility is one of the main reasons for its low bioavailability, however, it can be increased by preparing curcumin nanocrystals. In the experimental part, the effects of the composition of the background electrolyte (BGE) and the applied voltage on the curcumin nanocrystals were investigated. Background electrolytes were prepared using phosphoric acid, or HEPES and their pH was adjusted to 7.0 by NaOH, or TRIS, to test whether the shape of the peak is influenced by the ionic strength of BGE and not by the increasing concentration of a particular BGE component. Initial experiments did not involve voltage application, but only a pressure of 50 mbar. In following experiments both positive and negative voltages were applied, using a 10mM phosphate buffer, the pH of which was adjusted using TRIS. Most of the experiments were conducted using a 100nm curcumin nanocrystals sample. Curcumin nanocrystals provided an abnormally wide peak in both UV-VIS and LIF detection. It was found that the dispersion of the nanocrystal zone was not caused by diffusion,...
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Optimization of 5-fluorouracil determination by high-performance liquid chromatography
Durychová, Eva ; Křížek, Tomáš (advisor) ; Kozlík, Petr (referee)
This thesis is dedicated to the development of a method for the determination of 5-fluorouracil by high-performance liquid chromatography, which could be used for determination of its encapsulation efficiency by liposomes. First, separation of 1 mM standard of 5-fluorouracil was tested on several types of columns. Among tested columns belonged a C18 column, a C18 column with positive surface modification, a phenyl-hexyl column and several fluoride columns together with two HILIC columns. A mixture containing 10 mM CH3COONH4, pH = 4,5 and MeOH in the ratio of 98/2 was initially used as the mobile phase. The results showed, that 5-fluorouracil elutes on all columns too close to the dead time, where different impurities often elute. To avoid possible distortion of 5-fluorouracil signal by impurities potentially occurring in the real sample, several adjustments of chromatographic conditions were tested. The most effective solution was addition of 5 mM ion-pairing agent (namely tetrabutylammonium chloride hydrate) to the mobile phase, together with adjusting pH to 8,0 to support the ionization of the analyte. In the combination with mobile phase modified in this way, a phenyl-hexyl column with retention time 4,36 minutes reached the best result, therefore it was selected for the final determination of...
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